Safety tripping mechanism



Filed Nov. 9, 1965 June 6, 1967 J. J. ONDERKO 3,324,263

SAFETY TRPPING MECHANISM Filed Nov. 9, 1965 2 Sheets-Sheet 2 United States Patent C) 3,324,263 SAFETY TRHlPlNG MECHANESM `loseph l. fnderko, Phiiadelphia, Pa., assignor to l-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Fiied Nov. 9, 1965. Ser. No. 506,964 3 Claims. (Ci. ZOU- 114) This invention relates to molded case circuit breakers and more particularly relates to a safety tripping mechanism which will automatically trip the circuit breaker to its open circuit position in response to removal of the cover of the circuit breaker, and particularly that portion of the housing which covers a series-connected currentlimiting device.

ln m-olded case circuit breakers it is desirable to have a tripping feature which will automatically trip the breaker when the breaker cover, an end cover, an auxiliary cover, or a fuse cover is removed. Thus when an operator removes the cover of a circuit breaker for routine maintenance and/ or exchanging of parts, the breaker will automatically be tripped to its open circuit position thereby eliminating the possibility that the operator will be exposed to energized elements.

Although the instant invention will be described with respect to a series-connected current-limiting device, and circut iof the breaker frame type shown in co-pcnding United States patent application Ser. No. 465.313 entitled, Circuit Breaker Trip Unit Assembly, tiled June 21, 1965, in the names of Albert Strobel and John C. Brumeld, and assigned to the assignee of the instant invention, it is to be understood that the instant invention may find application in any circuit breaker wherein it is desirable to trip the breaker to its open circuit position in response to the removal of a protective cover portion of such circuit breaker.

As explained, for example, in Edmunds United States Patent No. 2,924,689, the mechanical and electrical coordination between a current-limiting device such as a fuse, and a circuit breaker unit, enables the use of a circuit breaker having a relatively low interrupting capacity for circuits having relatively high short circuit capacity. The circuit breaker unit is contained within its own housing, with the current-limiting devices being maintained in an aux-liary housng secured thereto such that the load terminal strap of the circuit breaker may be mechanically and electrically secured to the terminal strap of the fuse which is to be placed in electrical series therewith. The fuse containing auxiliary housing inclu-des a -cover which is removably secured t-o the circuit breaker housing.

ln accordance with the present invention, a safety tripping mechanism is provided on the circuit breaker for cooperating with the auxiliary cover. If such cover is removed, the safety tripping mechanism automatically trips the breaker to its open circuit position to protect an operator from coming into contact with energized parts of the circuit breaker.

The safety tripping mechanism includes a slide bar which is normally biased to an extended position in which a portion thereof extends beyond the position which the 'auxilary cover occupies when secured to the circuit breaker, and is positioned so as to be depressed by the auxiliary cover when it is secured to the circuit breaker. The slide bar is linked to a plunger which is normally biased to trip the circuit breaker for opening the contacts thereof. When auxiliary cover is placed on the breaker, it depresses the slide bar which thereby moves the plunger away from its tripping position. Removal of the cover frees the slide bar and allows the plunger to move to its tripping position which thereby trips the contacts of the breaker. In moving to its tripping position, the plunger also returns the slide bar to its extended position whereby it can be depressed when the cover is placed back on the breaker.

The slide bar and plunger are biased to their extended and tripping positions, respectively, (with the auxiliary cover removed) under the influence of a biasing spring interposed between the plunger head and a portion of the tripping mechanism mounting bracket. As a particularly advantageous feature of the instant invention the biasing spring has sufficient internal energy to move the plunger further than is necessary to assure tripping of the contacts. Such overtravel feature inherently compensates for spring fatigue in the future and thereby assures that no adjustment of the safety tipping mechanism will be required during the lifetime ofthe breaker.

As another advantage of the instant invention, the safety tripping mechanism is simple, of relatively few parts, and may be captively sub-assembled, as will be described in greater detail, for easy installation within the circuit breaker in which it is used.

Accordingly, it is an object of the instant invention to provide a safety tripping mechanism which will trip the contacts of a circuit breaker to their open circuit position in response to the removal of the cover of said circuit breaker.

It is another object of the instant invention to provide a safety tripping mechanism for use in a circuit breaker having a removable cover and a contact movable between closed circuit and open circuit positions, with such tripping mechanism including a slide bar disposed within the circuit breaker and normally biased toward a first position in which a portion thereof extends externally of the circuit breaker, such portion being depressed by the cover of the circuit breaker when it is placed thereon, and a plunger linked to the slide bar for movement in response to movement thereof, said plunger being normally biased toward a tripping position for tripping the contacts of the circuit breaker, and being movable to a non-tripping position in response to movement of the slide bar when the cover is placed on the circuit breaker.

Still another object of the instant invention is to provide such a safety tripping mechanism which includes biasing means for providing overtravel of the plunger thereby eliminating the necessity of adjustment during the lifetime of the circuit breaker in which the mechanism is used.

Yet another object of the instant invention is to provide such a safety tripping mechanism which can be captively sub-assembled with simplicity and easily mounted within a circuit breaker.

Other objects and a fuller understanding of the instant invention may be had by referring to the following description, taken in conjunction with the accompanying drawings, in which:

FIGURE l is a side view of a circuit breaker embody` ing the instant invention;

FIGURE 2 is a detailed view of a portion of FIGURE 1 showing the manner in which the safetyy tripping mechanism of the instant invention is released to trip the circuit breaker contacts in response to the removal of a cover portion of the circuit breaker; and y FIGURE 3 is a plan view of the safety tripping mechanism of the instant invention.

Referring rst to FIGURE 1, there is shown a circuit breaker unit 10 of the type shown and described in detail in the aforementioned co-pending application Ser. No. 465,313. As explained in greater detail in such application, the circuit breaker unit 10 includes a commercially available three-phase (only one phase of which is shown) molded case circuit breaker 12, which includes a plurality of cooperating contact pairs which are separable to interrupt the flow of current therethrough. The contact pair 3 of each phase is terminated on the load side by terminal strap 16.

Auxiliary current-limiting devices 18 in the form of fuses are connected in electrical series with each of the circuit breaker phases by means of the bolted connection of the fuse terminal strap 20 with the terminal strap 16. Terminal 22 extends from the opposite side of fuse 18 and provides the means by which the circuit being protected may be electrically secured to the circuit breaker unit 10. Cover 24 encloses the auxiliary current-limiting fuses 18 and is removably secured to the circuit breaker 12 by means of fastening elements 26. The current path between the line terminal strap 28 and the terminal 22 proceeds from stationary contacts 30, 32 to movable contacts 34 and 36 carried by contact arms 38 and 40 through flexible braids 42, contact carrier strap 44, trip unit strap 46, terminal strap 16, fuse strap 20 and fuse 18.

As seen most clearly in FIGURE 2, a magnetic trip assembly includes a magnetic member 56 and a movable actuating rod 48 having a trip actuating extension 50 which moves down into engagement with tripper bar extension member 52 of tripper bar 54.

Magnetic member 56 has a generally U-shaped configuration (only one upstanding arm 58 of which can be seen in FIGURE 2) having horizontally disposed pole faces 60 at the uppermost extremes of its spaced arm members 58. Movable armature member 62 (to which actuating rod 48 is secured for movement therewith) is horizontally positioned intermediate the plane of pole `faces 60 and the bottom surface 64 of a forwardly projecting extension 66 of the trip unit mounting bracket. Although not shown, the circuit breaker would nornally include an elongated bi-metallic element, the deflection of which will rotate the tripper bar 54 in response to a predetermined temperature rise caused by predetermined overload currents.

In operation, the tripper bar 54 is rotatable in response to deflection of the bi-metallic element of the thermal trip unit and in response to downward movement of the armature 62 in response to energization of the magnet member 56 caused by a fault current to release a latch member which disengages the circuit breaker cooperating contacts of each phase, in a Well known manner.

As mentioned previously, the breaker and series-connected current-limiting combination described above is intended only to illustrate one possible environment in which the instant invention may find application, and is in no Way intended to limit the invention to such environment. Contrary thereto, the instant invention may find application in any breaker in which it is desired to trip the breaker in response to removal of a cover portiton thereof.

In accordance with the instant invention a safety tripping mechanism, indicated generally at 68, is provided to rotate the tripper bar 54 and thereby effect opening of the circuit breaker contacts in response to removal of cover 24.

As can be best seen in FIGURES 2 and 3, the safety tripping mechanism 68 includes a generally L-shaped mounting bracket 70, one leg 72 of which is provided with a two-pronged finger-like extension 74 extending transversely therefrom. Extension 74 terminates in two fingerlike projections 76 Which are inserted Within suitably placed apertures in the forward projecting extension 66 of the trip unit mounting bracket. Leg 72 is also provided with a pair of apertures 78 (only one of which is seen in FIGURE 2) through which screws 80 may pass into screw-threaded engagement with the upstanding arms 58 of the magnetizing member 56 to further secure the safety tripping mechanism in position within the circuit breaker.

The other leg 82 of mounting bracket 70 includes a pair of slotted turned-in tabs 84 and 86 within which a slide bar 88 is movable between a first and second position (see FIGURES 2 and l, respectively). For reasons 4 to become apparent, the turned-in tab 84 is provided with a T-shaped slot 90.

Slide bar 88 is normally biased by a spring 89 toward its first position, FIGURE 2, in which a head portion 92 thereof extends externally of the circuit breaker, i.e., higher than or beyond the position which coverV 24 occupies when it is secured to breaker 12.

Slide bar 88 is integrally provided with an inwardly directed projecting finger 94 which is inserted within an enlarged aperture 96 of a linking member 98 which in turn is pivotally secured by a pivot pin 100 to the leg 82 of mounting bracket 70. Pivot pin 100 has an enlarged central portion 102 which resides between linking member 98 and the leg 82 of mounting bracket 70 to provide suitable spacing therebetween. Linking member 98 is freely mounted for rotation about pivot pin 100 in response to lineal movement of the slide bar 88 between its first position, FIGURE 2, and its second position, FIGURE 1, when the cover 24 is placed on the breaker 12 thereby depressing head portion 92.

A plunger 104 having a forked end 106 (see FIGURE 3) passes through leg 72 of bracket 70 and is pivotally linked to linking member 98 by means of a pin 108, an

' enlarged head portion 110 of which resides between leg 82 of bracket 70 and one prong of the forked end 106.

The plunger 184 is normally biased kby spring 89` toward a tripping position, in which a head portion 112 thereof rotates tripper bar 54 to release the tripping mechanism and thereby open the circuit breaker contacts. Plunger 104 is moved to a second position, against the bias of spring 89, when the cover 24 is placed on the breaker to depress slide bar 88 to its second position which thereby rotates linking member 98 in a counterclockwise direction with respect to FIGURE 2.

Upon removal of cover 24, slide bar 88 is freed and returns to its first position (FIGURE l) in response to rotation of linking member 98 caused by plunger 104 moving to its tripping position under the influence of spring 89. When head portion 112 hits tripper bar 54, the tripper bar is rotated counterclockwise with respect to FIGURE 2, to trip the circuit breaker contacts to their open circuit position under the influence of charged springs (not shown).

It is noted that spring 89 is suiiiciently charged to provide linear motion of plunger 104 far in excess of the amount of linear motion necessary to rotate tripper bar 54. Such overtravel feature compensates for later spring' fatigue and guarantees that no further adjustment will be necessary during the lifetime of the safety tripping mechamsm.

The safety tripping mechanism of the instant invention may be sub-assembled with simplicity and mounted within the circuit breaker unit 10 in such a manner as to materially reduce possibility of malfunction. Specifically, the linking member 98 is rst held perpendicular to the side of the circuit breaker (i.e., perpendicular to the plane of the paper in FIGURE 2) and in engagement with the forked end of plunger 104. The freely movable pivot pin 108 is now inserted from the bottom and held in place while the linking member 98 is rotated 90 downward over the pivotl pin 100 which has been momentarily held in place such that its enlarged central portion 102 abuts the leg 82 of mounting bracket 70. Finally, the sliding bar 88 is inserted in the slotted turned-in tabs 84 and 86 (with the T-shaped slot of tab 84 allowing the inwardly projecting finger 94 to pass therethrough) until the projecting nger 94 can be inserted with the aperture 96 in linking element 98.

It will be appreciated that in the final assembly, the head portion 110 of pin 108 is trapped between the forked end 106 of plunger 104 and the leg 82 of mounting bracket 70, and also that the enlarged central portion 102 of pin is trapped between the linking member 98 and the side wall 82 of mounting bracket 70. The complete subassembly may be easily secured within the circuit breaker by inserting depending projections 76 of the finger-like extension 74 into the apertures provided in the forward projetcing extension 66 of the trip unit mounting bracket while simultaneously passing screws 80 through leg 72 of mounting bracket 70 and into engagement with tapped apertures in the magnetizing member 56.

Thus there has been described a safety tripping mechanism which automatically trips the contacts of a cooperating circuit breaker to their open circuit position in response to removal of the cover of such circuit breaker. The instant invention is provided with an overtravel feature which assures that the circuit breaker will be tripped in response to removal of its cover in a manner which eliminates the necessity of adjustment of the mechanism during the lifetime of the breaker. Additionally, the safety tripping mechanism of the instant invention may be captively sub-assembled with simplicity within the cooperating circuit breaker in a manner which eliminates additional retaining structure and assures continual operation thereof. n

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited not by the specific disclosure herein, but only by the appending claims.

What is claimed is:

1. In combination, a circuit breaker, said -circuit breaker having a removable cover, a contact movable between closed circuit and open circuit positions to interrupt the flow of current therethrough, a tripper bar connected with said contact and movable between a latching and releasing position for tripping said contact from its said closed circuit to its said open circuit position, and a safety tripping mechanism connected with said tripper bar for moving said tripper bar to its said releasing position in response to removal of said cover, said mechanism comprising:

a slide bar disposed for lineal movement within said circuit breaker, said slide bar being normally biased toward a first position in which a portion thereof extends externally of said circuit breaker, said portion being in position to be depressed by said cover to move said slide bar to a second position when said cover is placed on said circuit breaker;

a linking member pivotally secured to said circuit breaker, said linking member being pivotally secured at one point thereof to said slide bar, lineal movement of said slide bar between its first and second positions effecting rotation of said linking member; and

a plunger pivotally secured to a second point of said linking member for lineal movement within said circuit breaker in response to rotation of said linking member, said plunger having a head portion, biasing means connected with said plunger, said plunger being normally biased by said biasing means toward a first position in which said head portion thereof engages said tripper bar to maintain said tripper bar in its releasing position, said plunger being movable to a second position, in which said head porting is away from said tripper bar, in response to rotation of said linking member caused by lineal movement of said slide bar from its first position to its second lposition in response to said cover depressing said portion of the slide bar when said cover is placed on said circuit breaker;

removal of said cover freeing said slide bar thereby allowing said plunger to move toward its first position whereby said head portion will engage said tripper bar to move it from its latching to its releasing position to trip said contact to its open circuit position, movement of said plunger to its first position further causing rotation of said linking means to thereby return said slide bar to its first position.

2. The combination of claim 1, and further including a mounting bracket for housing said safety tripping mechanism, said linking member having a slot at said one point thereof, said slide bar including a projection which extends into said slot provided in said linking member, a freely rotatable pivot pin, said plunger being pivotally secured to said linking member by means ofsaid freely rotatable pivot pin passing through said linking member at said second point thereof and said plunger, said pivot pin having a longitudinal axis, said mounting bracket having a first wall, said pivot pin being prevented from movement along its said longitudinal axis by said first wall of said mounting bracket and said plunger.

3. The combination of claim 2, wherein said slide bar is biased toward its first position and said plunger is biased toward its first position under the influence of said biasing means, said biasing means comprising a spring interposed between the head portion of said plunger and said mounting bracket.

4. The combination of claim 3, wherein the distance said plunger travels between its second position and its first position under the influence of said spring is greater than the distance necessary to move said tripper bar between its latching and releasing positions.

5. In combination, with a circuit breaker, said circuit breaker having a removable cover, a contact movable between closed circuit and open circuit positions to interrupt the flow of current therethrough, a tripper bar connected with said contact and movable between a latching and a releasing position for tripping said Contact from said closed circuit to said open circuit position, and a safety tripping mechanism connected -With said tripper bar for moving said tripper bar to said releasing position in response to removal of said cover, said mechanism comprising:

a mounting bracket which is generally L-shaped and having first and second legs, said first leg having a pair of slotted turned-in tabs extending transversely therefrom, said second leg having an aperture therethrough;

a slide bar disposed for lineal movement within said slotted turned-in tabs, said slide bar being normally biased toward a first position in which a portion thereof extends externally of said circuit breaker, -said portion being in position to be depressed by said cover to move said slide bar to a second position when said cover is placed on said circuit breaker;

a linking member pivotally secured to said first leg of said mounting bracket, said linking member being pivotally secured at one point thereof to said slide bar, lineal movement of said slide bar between its first and second positions effecting rotation of said linking member; and

a plunger passing through said aperture, said plunger being pivotally secured to a second point of said linking member for lineal movement within said circuit breaker in response to rotation of said linking member, said plunger having a head portion, biasing means connected with said plunger. said plunger being normally biased by said biasing means toward a first position in which said head portion thereof engages said tripper bar to maintain said tripper bar in its releasing position, said plunger being movable to a second position, in which said head portion is away from said tripper bar, in response to rotation of said linking member caused by lineal movement of said slide bar from its first position to its second position in response to said cover depressing said portion of the slide bar when said -cover is placed on said circuit breaker;

removal of said cover freeing said slide bar thereby allowing said plunger to move toward its first position whereby said head portion will engage said tripper bar to move it from its latching to its releasing position to trip said contact to its open circuit position, movement of said plunger to its rst position further causing rotation of said linking means to thereby return said slide bar to its rst position.

6. The combination of claim 5, wherein said slide bar has an integrally connected depending projection and said linking member has an opening at said one point thereof, said slide bar being pivotally secured to said linking member by means of said integrally connected depending projection which extends from said slide bar into said opening provided in said linking member at said one point thereof, one of said slotted turned-in tabs having a slot which is Tishaped to accommodate the passage of said projection therethrough.

7. The combination of claim 6, including a rst freely rotatable pivot pin, said plunger being pivotally secured to said linking member by means of said rst freely rotatable pivot pin passing through said linking member at said second point thereof and said plunger, said first pivot pin including an enlarged head portion which is captively held between said rst leg of said mounting bracket and said plunger to prevent motion of said rst pin along its longitudinal axis.

8. The combination of claim 7, including a second freely rotatable pivot pin, said linking member being pivotally secured to said first leg of said mounting bracket by means of said second freely rotatable pivot pin passing through said linking member and said rst leg; said second pin having an enlarged central portion which is captively held between said rst leg and said linking member.

References Cited UNITED STATES PATENTS 2,824,689 2/1960 Edmunds i 200--114 2,939,936 6/1960 Deans 200-116 3,032,629 5/1962 Uecker 20G-114 BERNARD A. GILHEANY, Primary Examiner.

H. E. SPRINGBORN, Assistant Examiner. 

1. IN COMBINATION, A CIRCUIT BREAKER, SAID CIRCUIT BREAKER HAVING A REMOVABLE COVER, A CONTACT MOVABLE BETWEEN CLOSED CIRCUIT AND OPEN CIRCUIT POSITIONS TO INTERRUPT THE FLOW OF CURRENT THERETHROUGH, A TRIPPER BAR CONNECTED WITH SAID CONTACT AND MOVABLE BETWEEN A LATCHING AND RELEASING POSITION FOR TRIPPING SAID CONTACT FROM ITS SAID CLOSED CIRCUIT TO ITS SAID OPEN CIRCUIT POSITION, AND A SAFETY TRIPPING MECHANISM CONNECTED WITH SAID TRIPPER BAR FOR MOVING SAID TRIPPER BAR TO ITS SAID RELEASING POSITION IN RESPONSE TO REMOVAL OF SAID COVER, SAID MECHANISM COMPRISING: A SLIDE BAR DISPOSED FOR LINEAL MOVEMENT WITHIN SAID CIRCUIT BREAKER, SAID SLIDE BAR BEING NORMALLY BIASED TOWARD A FIRST POSITION IN WHICH A PORTION THEREOF EXTENDS EXTERNALLY OF SAID CIRCUIT BREAKER, SAID PORTION BEING IN POSITION TO BE DEPRESSED BY SAID COVER TO MOVE SAID SLIDE BAR TO A SECOND POSITION WHEN SAID COVER IS PLACED ON SAID CIRCUIT BREAKER; A LINKING MEMBER PIVOTALLY SECURED TO SAID CIRCUIT BREAKER, SAID LINKING MEANS BEING PIVOTALLY SECURED AT ONE POINT THEREOF TO SAID SLIDE BAR, LINEAL MOVEMENT OF SAID SLIDE BAR, BETWEEN ITS FIRST AND SECOND POSITIONS EFFECTING ROTATION OF SAID LINKING MEMBER; AND 